Inflammatory events have been implicated in a variety of middle ear disorders, including serous otitis media in its various forms. The investigation of etiology and management of such disorders has been hampered by a lack of basic knowledge concerning the mechanisms of immune response in the middle ear. It is the objective of the proposed research to develop an animal model of middle ear inflammation in the guinea pig, and to investigate the basic response of the middle ear to antigenic stimulation. Keyhole limpet hemocyanin, a potent antigenic stimulus, will be the standard antigen for all experiments. The primary, or immediate, response of the middle ear to a single application of antigen will be evaluated at three dosage levels. Time course, immunoglobulin subclasses and activation of cell mediated immunity will be measured, utilizing antigen binding capacity, immunoelectrophoresis, lymphocyte transformation response and migration inhibition factor production. Both the local immune response of the middle ear mucosa and the systemic response resulting from middle ear antigenic sensitization will be measured. The secondary, or delayed, immune response elicited by challenge of the middle ear of previously sensitized animals will be similarly examined, and will also be assessed by otoscopy and impedance audiometry.